The aims of this investigation are to continue efforts to derive and to examine in vitro and in vivo the biological properties of long-term cultured, selected and cloned tumor-specific T-cell lines. Experiments already completed give confidence that T-cell lines which bear tumor specificity can be raised against chemically induced murine sarcomas. These lines can be sustained for sufficiently long periods and in sufficiently high numbers for a wide range of biological studies and can be tested for the capacity to protect against tumor growth in vivo in potential immunotherapeutic models. Efforts will be channeled into three specific areas of investigation. (1)\To continue to raise and to sustain a library of antitumor T-cell lines of both cytotoxic and helper phenotypes to examine them for in vivo protection against tumor growth. (2)\To assess the specificity of tumor control by cloned lines, dose-response relationships, routes of administration and related factors including provision for continuing requirements for growth factors, required to inhibit established tumor growth. (3)\To examine the role of the MHC in restricting the in vitro killing or controlling of tumor growth in vivo. In this context, the hypothesis will be tested that T cells which have specificity directed toward common tumor-associated antigens (for example, retrovirus products) kill successfully only if the antigen is seen in the context of a uniquely disordered MHC presented on the individual tumor membrane. This proposition implies that the TSTA is not a unique antigen but simply an altered normal MHC expression.